Dynamic Oxygen Control in Nitritation Denitritation Reactors
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Solution Overview
Problem
Current biological water treatment processes for reducing nitrogen pollution, such as nitrification-denitrification, are inefficient due to high oxygen and carbon consumption, and struggle to dynamically optimize oxygen supply to prevent nitrate formation.
Innovation Solution
A method that dynamically adjusts oxygen supply in a biological reactor based on the ratio of nitrates formed to ammonium broken down and the percentage of ammonium reduced, promoting the activity of AOB bacteria over NOB bacteria to limit nitrate production while maintaining effective ammonium reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nitrification-denitrification process is used to reduce nitrogen pollution, then nitrogen removal effectiveness is improved, but oxygen consumption increases significantly
Solution Approach 1:
The patent implements dynamic control of the aeration system by continuously monitoring nitrate concentration and adjusting oxygen supply in real-time. The aeration intensity varies during different phases of the treatment cycle, providing high oxygen during nitritation when needed and reducing or stopping aeration during denitritation to prevent nitrate formation, thereby optimizing energy efficiency while maintaining nitrogen removal effectiveness
Solution Approach 2:
The patent changes operational parameters including dissolved oxygen concentration, aeration time, and oxygen supply rate based on the treatment phase and measured nitrate levels. By adjusting these parameters dynamically, the system achieves complete ammonium oxidation to nitrogen gas while minimizing oxygen consumption compared to conventional continuous aeration systems
2Manufacturing precision
If aeration is increased to ensure complete ammonium oxidation, then nitrogen transformation completeness is improved, but nitrate formation increases
Solution Approach 1:
The patent employs periodic aeration cycles with distinct nitritation and denitritation phases. During nitritation, aeration is provided to oxidize ammonium to nitrite. During the subsequent anoxic denitritation phase, aeration is stopped or reduced, allowing heterotrophic bacteria to convert nitrite to nitrogen gas using organic carbon as electron donor. This periodic action ensures complete ammonium oxidation while preventing nitrate formation by avoiding oxygen presence during the denitritation phase
Solution Approach 2:
The patent implements feedback control by continuously monitoring nitrate concentration in the reactor and using this information to adjust aeration intensity and duration. When nitrate levels are detected, the system reduces or stops aeration to prevent further nitrate formation while maintaining ammonium oxidation completeness through precise control of oxygen supply
3Reliability
If carbon source is added to support heterotrophic denitrification, then nitrate reduction capability is improved, but treatment cost increases
Solution Approach 1:
The patent utilizes the organic carbon already present in the effluent being treated to support heterotrophic denitrification, rather than adding external carbon sources. The system is designed to leverage the substrate available in the waste stream itself, eliminating or reducing the need for costly carbon supplements while maintaining effective nitrate and nitrite reduction capabilities
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the efficiency of ammonium reduction and reduces oxygen consumption, thereby improving the economic viability of the treatment process while minimizing nitrate formation.
Implementation Method 1
the injection of oxygen into the reactor promotes the development of an autotrophic nitrifying biomass allowing the transformation of nitrogen into the form of ammonium
Implementation Method 2
a biomass transforming nitrites (NO2- nitrite oxidizing bacteria)
Implementation Method 3
stopping the aeration of the reactor promotes the development of a denitrifying biomass which reduces the nitrates to molecular gaseous nitrogen (dinitrogen) N2 via the nitrite stage
Data Source
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AI summary
The invention relates to a method for treating water, containing nitrogen in the form of ammonium, within a biological reactor (10) by means of nitrosation/denitrosation, said method including at least a step (i) of feeding said water into said biological reactor (10), an aeration step (ii) during which oxygen is injected into the reactor (10), a step (iii) for extracting treated water from said reactor (10), determination steps being carried out continuously or intermittently at a predetermined frequency. According to the invention, such a method includes a step of calculating the ratio between information representative of the quantity of nitrates formed in said reactor and information representative of the quantity of ammonium broken down in said reactor, and a step of determining the percentage of ammonium broken down in said reactor (10), the oxygen supplied to said reactor during said aeration step (ii) being predetermined on the basis of ratio between said information representative of the quantity of nitrates formed in said reactor (10) and said information representative of the quantity of ammonium broken down in said reactor (10), and on the basis of said percentage of ammonium broken down in said reactor (10).